The beginning of human personhood is the moment when a human is first recognized as a person. There are differences of opinion about the precise time when human personhood begins and the nature of that status. The issue arises in a number of fields, including science, religion, philosophy, and law, and is most acute in debates about abortion, stem cell research, reproductive rights, and fetal rights.
Traditionally, the concept of personhood has included the concept of the soul, a metaphysical concept of a non-corporeal or extra-corporeal dimension of human beings. In modernity, the concepts of subjectivity and intersubjectivity, personhood, mind, and self have come to encompass a number of aspects of humanness that were previously considered to be characteristics of the soul. One question about the beginning of human personhood has been the moment at which soul enters the body. An alternative question, both historically and in modern times, may be at what point does the developing individual acquire personhood or selfhood.
Issues relating to the question of the beginning of human personhood include the legal status, bodily integrity, and subjectivity of mothers, and the philosophical concept of natality, i.e. "the distinctively human capacity to initiate a new beginning" that a new human life embodies.Charles E. Rice, The Dred Scott Case of the Twentieth Century, Houston Law Review, 10:1059, 1972-1973
Discussions of the beginning of personhood may be framed in terms of the moment life begins. James McGrath and others argue the beginning of personhood begins is not interchangeable with the beginning of a human life. According to Jed Rubenfeld, the terms human being and person are not necessarily synonymous.
Biological markers
Embryologist Scott Gilbert states: There is no consensus among biologists as to when personhood begins. Different biologists have proposed that personhood begins at such events as fertilization, gastrulation, the acquisition of an EEG pattern, and birth. Other scientists claim that the acquisition of personhood is gradual or that the question of personhood is not a biological one.
Fertilization
Fertilization is the fusing of the gametes; a sperm cell and an ovum (egg cell) fuse to form a single-cell zygote. This is the beginning of the diploid phase of the human life cycle after two genetically unique haploid cells created via meiosis and chromosomal translocation combine their DNA and begin to develop into a multi-cellular organism. The zygote is genetically distinct from each of its parents.
The process of fertilization lasts around 24 hours. Many zygotes die shortly after fertilization, most often due to chromosomal abnormalities. Estimates of the percentage that die prior to implantation vary from 10% to 70%. Those that fail to implant in the uterine wall are sloughed off with the endometrial lining during menstruation. Of those that implant, many are miscarried, often without the woman knowing she was pregnant; estimates of post-implantation loss also vary considerably. As cleavage (cellular division) occurs, a single zygote may split into two or three zygotes, resulting in monozygotic ("identical") twins or triplets. At other times, two individually fertilized zygotes may fuse into one zygote, which is known as a chimera.
According to some commentators, life begins at the point of fertilization. Charles E. Rice said Bradley M. Patten in Foundations of Embryology wrote the union of the sperm and the ovum "initiates the life of a new individual", beginning "a new individual life history". Rice also quotes Herbert Ratner in A Doctor Talks About Abortion: "It is now of unquestionable certainty that a human being comes into existence precisely at the moment when the sperm combines with the egg". Ratner said this knowledge comes from the study of genetics. At fertilization, all of the genetic characteristics, such as the color of the eyes, "are laid down determinatively". In the college text book Psychology and Life, Floyd L. Ruch wrote: "At the moment of conception, two living germ cells (sperm and egg) unite to produce an individual". James C. G. Conniff wrote: "At that moment conception takes place and, scientists generally agree, a new life begins—silent, secret, unknown".
Implantation
In his book Aborting America, Bernard Nathanson said implantation should be considered the point at which life begins. He stated: "Biochemically, this is when alpha [the unborn human] announces its presence as part of the human community by means of its hormonal messages, which we now have the technology to receive. We also know biochemically that it is an independent organism distinct from the mother." In their book When Does Human Life Begin?, John L. Merritt and his son J. Lawrence Meritt II said if "the breath of life" (Genesis 2:7) is oxygen, then a blastocyst starts taking in the breath of life from the mother's blood at the moment it successfully implants in her womb, which usually happens nine days after fertilization. According to Goldie Milgram, Jewish tradition interprets the biblical phrase "breath of life" as the Earth's atmosphere, and that life starts when the baby's head emerges from the mother's body and takes its first breath of air.
Gastrulation
Non-conjoined monozygotic twins can form up to day 14 of embryonic development; when twinning occurs after 14 days, the twins will likely be conjoined. Gastrulation occurs at 14 days and is the stage at which non-conjoined twins can no longer form. According to Bonnie and Vern Bulloch, an early embryo cannot be a person because "If every person is an individual, one cannot be divided from oneself". Norman Ford stated: "the evidence would seem to indicate not that there is no individual at conception, but that there is at least one and possibly more". He went on to support the idea, similar to processes in other species, one twin could be the parent of the other asexually. Theodore Hall agreed with the plausibility of this explanation, saying: "We wonder if the biological process in twinning isn't simply another example of how nature reproduces from other individuals without destroying that person's or persons' individuality". Gilbert quotes bioethicist Robert Green as saying: "Only at gastrulation can we say that the lengthy process of individuation is complete".
Brain function (brain birth) According to D.G. Jones, there are two types of brain death—whole brain death, the irreversible cessation of function of both the brain stem and higher parts of the brain—and higher-brain death, destruction of the cerebral hemispheres alone, with possible retention of brain stem function; and analogously, there are two types of brain birth based on their reversal—brain-stem birth at the first appearance of brain waves in lower brain (brain stem) at 6–8 weeks of gestation, and higher-brain birth at the first appearance of brain waves in higher brain (cerebral cortex) at 22–24 weeks of gestation.
Fetal viability
The perspective of Planned Parenthood, a major abortion provider in the United States, is based on fetal viability. It stated: Until the fetus is viable, any rights granted to it may come at the expense of the pregnant woman, simply because the fetus cannot survive except within the woman's body. Upon viability, the pregnancy can be terminated, as by a c-section or induced labor, with the fetus surviving to become a newborn infant. Several groups believe that abortion before viability is acceptable, but is unacceptable after."
In some countries, early abortions are legal in all circumstances but late-term abortions are limited to circumstances in which there is a clear medical need. There is no sharp limit of development, gestational age, or weight at which a human fetus automatically becomes viable.Moore, Keith and Persaud, T. The Developing Human: Clinically Oriented Embryology, p. 103 (Saunders 2003). A 2013 study said: "While only a small proportion of births occur before 24 completed weeks of gestation (about 1 per 1000), survival is rare and most of them are either fetal deaths or live births followed by a neonatal death".
Birth Some commentators believe while the fetus is still inside the mother's body, whether it is viable or not, it has no rights of its own. In some interpretations of Jewish law, life begins at first breath; other interpretations state: "the unborn child, although a living being, does not yet have a status of personhood equal to its mother".
Whether this is a scientific question
Some biologists say the beginning of personhood is not a question they can answer. In 1981, Senator Jesse Helms introduced a Human Life Bill that said: "Congress finds that present day scientific evidence indicates a significant likelihood that actual human life exists at conception" and that 'person' shall include all human life as defined herein", provoking a response from many scientists and medical professionals. The National Academy of Sciences passed a resolution saying the question of whether human life exists from conception was "a question to which science can provide no answer ... Defining the time at which the developing embryo becomes a person must remain a matter of moral or religious value". A group of over 1,200 scientists signed a petition that said: "As scientists we agree that science cannot define the moment at which 'actual human life' begins and consider that the attempt to reach a scientific resolution of this question represents a misuse and misunderstanding of science". A series of Senate hearings were also held, and many scientists and medical professionals testified. Some said life begins at conception but others said this was not a question answerable by science. Lewis Thomas said: "whether the very first single cell that comes into existence after fertilization of an ovum represents in itself a human life, is not in any real sense a scientific question and cannot be answered by scientists ... it can be argued by philosophers and theologians, but it lies beyond the reach of science." Frederick Robbins said: "the question of when life begins is not in essence, a scientific matter. Rather it is one that evokes complicated ethical and value judgments. In fact, I doubt whether the health sciences can shed much light on such moral questions."
Other markers There are also other ideas of when personhood is achieved: at ensoulment, or quickening at "formation" – an early concept of bodily development (see preformationism). at the emergence of consciousness at the emergence of rationality (see Immanuel Kant)
Human personhood may also be seen as a work in progress, with the beginning being a continuum rather than a moment in time.Human Being and Human Person: Jacques Maritain's Notion of the Person in the Contemporary Setting Francesco E.M. Giordano, General Studies in the Humanities 345. The University of Chicago. Professor Bernard Schumacher, PhD. 15 November 2001
Individuation Philosophers such as Aquinas use the concept of individuation. They say abortion is not permissible from the point at which individual human identity is realized. According to Anthony Kenny, this can be derived from everyday beliefs and language, and one can say: "if my mother had an abortion six months into her pregnancy, she would have killed me", then one can reasonably infer at six months, the me in question would have been an existing person with a valid claim to life. Because division of the zygote into twins through the process of monozygotic twinning can occur until the fourteenth day of pregnancy, Kenny says individual identity is obtained at this point and thus abortion is not permissible after two weeks.
Quickening